The present invention relates to a piezoelectric vibrator unit wherein internal electrodes are laminated in a direction of a stretching axis, a method of manufacturing the piezoelectric vibrator unit as a pressure generating member.
In an ink-jet recording head using a piezoelectric vibrator in a longitudinal vibration mode, as disclosed in Unexamined Japanese Patent Publication No. Hei 4-1052, elastic plates are arranged on the back surface of a nozzle plate in which plural nozzles are made at a narrow interval, and a piezoelectric vibrator with the piezoelectric constant of d31 divided corresponding to each pressure generating chamber in a passage forming substrate is touched to the back surface of the elastic plate so that ink from a reservoir is led to the pressure generating chamber via an ink supply port, ink in the pressure generating chamber is pressurized by the piezoelectric vibrator driven according to a recording signal and jetted from a nozzle aperture as an ink droplet.
As such a piezoelectric vibrator with the piezoelectric constant of d31 has a smaller piezoelectric constant, compared with a piezoelectric vibrator with the piezoelectric constant of d33 because a piezoelectric vibrator having the constant d31 utilizes displacement in a direction perpendicular to a direction in which internal electrodes are laminated as well-known, there is a problem that rigidity for bending stress is small and breakage is readily caused in a process for forming a vibrator in predetermined size by cutting one piezoelectric diaphragm by a dicing cutter, a wire saw and others because the above piezoelectric vibrator is formed long and narrowly and constituted as a cantilever that one end is fixed to a supporting substrate and a fixing substrate.
To solve such a problem, as disclosed in Unexamined Japanese Patent Publication No. Hei 6-226971, there is proposed a piezoelectric vibrator wherein common internal electrodes and individual internal electrodes are laminated with piezoelectric material so that the above electrodes are wrapped in a central area and the respective electrodes are exposed only at one end, and each lower end of piezoelectric vibrators with the piezoelectric constant of d33 is attached to a fixing substrate at the same pitch as the arrangement pitch of pressure generating chambers in a passage unit.
Hereby, large displacement by the piezoelectric constant of d33 can be obtained, however, as a conductive layer for supplying a driving signal to the common internal electrodes and the individual internal electrodes is divided into the surface and the back surface of the fixing substrate, there is a problem that the connection of a flexible cable is difficult. In addition, as the bottom of the piezoelectric vibrator is fixed to the fixing substrate, the bonding area is limited to the cross section of the piezoelectric vibrator and thereby the strength of bonding is low.
A piezoelectric vibrator unit according to the present invention comprises: a plurality of piezoelectric vibrators including a vibrational area in which common internal electrodes and individual internal electrodes are laminated so that they are wrapped in a central area in a displacement direction thereof with a piezoelectric material between the both internal electrodes and one end portions of the respective electrodes are exposed only on one of the side faces; a first conductive area which conducts both of common internal electrode which is exposed on the side of the fixing substrate and the other side face of the piezoelectric vibrator via the conductive material; and a second conductive area formed on the other side face of the piezoelectric vibrator to conduct to the individual internal electrode.
Accordingly, one side face of the piezoelectric vibrator can be fixed to the fixing substrate as a bonding face, thereby desired bonding strength can be obtained independent of a cross section of the piezoelectric vibrator. In addition, since the conductive area conducting to the common internal electrodes and the conductive area conducting to the individual internal electrodes are located on the same face, a cable can be connected to the conductive layers on the same face.
Therefore, a first object of the present invention is to provide a piezoelectric vibrator unit wherein a cable can be connected to the surface of a piezoelectric vibrator in an arranging direction thereof, and bonding area between the piezoelectric vibrator and a fixing substrate can be sufficiently secured.
A second object of the present invention is to propose a method of manufacturing the piezoelectric vibrator unit suitable for a recording head.
A third object of the present invention is to provide an ink-jet recording head using the above piezoelectric vibrator unit.